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Western Pygmy Rattlesnake

Viperidae (vipers and pit vipers) in the order Squamata (lizards and snakes)

Description:

A small, colorful rattlesnake with a slender tail and tiny rattle. General color is light brownish gray, with a row of small, dark brown spots on the back and similar spots on each side. Most specimens also have a rust-colored stripe down the back. The belly is usually gray or dusky cream-colored, with numerous irregularly spaced bars. The head has a distinct black stripe that angles from the eye to the corner of the mouth, and a sensory pit located between each nostril and eye. The tail is thin and has a tiny rattle.

The disposition of this rattlesnake varies from individual to individual. Some will try to defend themselves vigorously by coiling, sounding their rattles, jerking their head, and striking at any movement. Others remain motionless and try to escape only when touched by a stick or snake hook. The sound of the vibrating rattle is a faint buzz, like the sound of a grasshopper, and can be heard for only about a yard away.

Size:

Length: 15 to 20 inches. One of the smallest species of rattlesnakes in North America.

Habitat and conservation:

Prefers south-facing, rocky, partially wooded hillsides, near glades, in woods near rock ledges, and along the margins of forests and meadows. In late spring and early summer, it basks in rocky open areas, near brushpiles, or along roadsides near forests and glades. In July and August it tends to be nocturnal and can be seen crossing roads at night. It takes shelter under rocks in spring, early summer, and autumn. It also retreats into abandoned small mammal burrows, logs, and brushpiles.

Foods:

Food includes a variety of lizards, small snakes, mice, and occasionally small frogs and insects. Like other rattlesnakes, western pygmy rattlesnakes have hollow fangs to inject venom into their prey, and heat-sensitive pits between the eyes and nostrils that allow them to detect and accurately strike warm-blooded prey (such as rodents) even in total darkness.

Distribution in Missouri:

Extreme southern Missouri along the border with Arkansas, and in the eastern Missouri Ozarks and St. Francois Mountains.

Life cycle:

This species is normally active from mid-April to mid-October. Courtship and breeding apparently occur in the spring, and young are born from late August through September, with 3–7 young per litter. Newborns are paler than the adults, have a yellow tail tip, and are about 4–7½ inches long. In our state, it appears that females typically only breed every other year.

Human connections:

This small species is so secretive that few people encounter it. Although its bite is not fatal, a bite victim should seek immediate medical attention. The western pygmy rattlesnake should be respected and left alone. In extreme southern Missouri, this snake is called the “ground rattler.”

Ecosystem connections:

Rattlesnakes are considered the most evolutionarily advanced group of snakes. In addition to hollow fangs and heat-detecting facial pits, their tail rattles warn would-be predators not to attack them. Yet rattlesnakes are often preyed upon by hawks, kingsnakes, and other predators.

Missouri’s largest venomous snake is dangerously venomous, but there are few cases of rattlesnake bites in our state. It frequents rough country, is mostly nocturnal in summer and few Missourians ever encounter it.

This shy, reclusive, nonaggressive rattlesnake used to live in floodplain wetlands of the Mississippi, Missouri and Grand rivers, but as those wetlands have been drained and destroyed, the massasauga has disappeared with them. Now it is an endangered species.

Regs and Areas

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